I put the mine on today. I like it so far. I understand the 2 complaints I've read:
1-It pops off when you lean on it. Not if you tighten it firmly. I can see by how it's attached that someone may not understand that it needs to be VERY FIRMLY attached. Finger tight just doesn't cut it.
2-It's too low. Depending on your chair size, and your size, it could be too low. I have a "B" sized chair, and I am 6" tall, normal proportions. The headrest is about 10"x6.5" with the bottom of the headrest about 2"-3" above the top of the chair back. If your chair was a high-back, the back of your head would be making contact, that is what we are used to. The headrest makes contact from the back of my head down to the bottom of my neck, a cradling feeling. The headrest tilts. If you are 6-2"+ it could be a little too low.
I'm looking at it and can't see what I might have a problem with. It's appearance is nicer than the photos. It's a headrest. Other than it popping off or being too low, I think I'm good with it. 3 days of use and I can be more definitive.